Internal combustion engines today utilize electronic controls to achieve optimal engine operation. Typically, the electronic control systems include a primary control unit for processing control algorithms and a variety of sensors for providing control signals to the primary control unit. One important sensor for achieving optimal engine control is a mass fluid flow sensor for measuring air intake into the internal combustion engine.
It is important that the mass fluid flow measurement is accurate in order to provide optimal engine operation. One significant problem affecting the mass fluid flow measurement, is reverse flow or back flow in the direction opposite of engine air intake. Typically, mass fluid flow sensors detect the flow of air in both the forward and reverse directions relative to air intake, therefore reverse flow causes an inaccurate mass fluid flow reading.
Prior art mass fluid/air flow devices have attempted to address this problem by providing mass air flow sensor configured as disclosed in U.S. Pat. No. 5,563,340 issued to Clowater et al. in Clowater, a mass air flow sensor having a U-shaped air passage and a longitudinally converging elliptical inlet configuration is disclosed, and hereby incorporated by reference. This configuration increased measurement efficiency and reduced the effect of back flow on the measurement of mass air flow into the internal combustion engine. Further, such a configuration produces advantageously low signal to noise ratio, as well as high velocity flow across the mass fluid flow sensor element.
While prior art mass fluid/air flow sensors, such as the one disclosed in Clowater, significantly improved the accuracy of the mass fluid flow measurement improvements are still needed to address other problems. For example, it would be advantageous to provide a mass fluid/air flow sensor that provided enhanced cooling control of the sensing elements used to detect the mass of the flowing fluid. Such enhanced cooling control of the sensing elements provides a more accurate reading of the mass of the flowing fluid.